EP1449004A1 - Sequence de reconstruction de projection de type a echo de gradient multiple destinee a une irm et notamment a une irm a diffusion ponderee - Google Patents

Sequence de reconstruction de projection de type a echo de gradient multiple destinee a une irm et notamment a une irm a diffusion ponderee

Info

Publication number
EP1449004A1
EP1449004A1 EP02782317A EP02782317A EP1449004A1 EP 1449004 A1 EP1449004 A1 EP 1449004A1 EP 02782317 A EP02782317 A EP 02782317A EP 02782317 A EP02782317 A EP 02782317A EP 1449004 A1 EP1449004 A1 EP 1449004A1
Authority
EP
European Patent Office
Prior art keywords
gradient
set forth
diffusion
magnetic resonance
imaging region
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP02782317A
Other languages
German (de)
English (en)
Other versions
EP1449004B1 (fr
Inventor
Jukka I. Tanttu
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Philips North America LLC
Philips Nuclear Medicine Inc
Original Assignee
Koninklijke Philips Electronics NV
Philips Medical Systems Cleveland Inc
Philips Medical Systems Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics NV, Philips Medical Systems Cleveland Inc, Philips Medical Systems Inc filed Critical Koninklijke Philips Electronics NV
Publication of EP1449004A1 publication Critical patent/EP1449004A1/fr
Application granted granted Critical
Publication of EP1449004B1 publication Critical patent/EP1449004B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/563—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution of moving material, e.g. flow contrast angiography
    • G01R33/56341—Diffusion imaging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R33/00—Arrangements or instruments for measuring magnetic variables
    • G01R33/20—Arrangements or instruments for measuring magnetic variables involving magnetic resonance
    • G01R33/44—Arrangements or instruments for measuring magnetic variables involving magnetic resonance using nuclear magnetic resonance [NMR]
    • G01R33/48—NMR imaging systems
    • G01R33/54—Signal processing systems, e.g. using pulse sequences ; Generation or control of pulse sequences; Operator console
    • G01R33/56—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution
    • G01R33/561—Image enhancement or correction, e.g. subtraction or averaging techniques, e.g. improvement of signal-to-noise ratio and resolution by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences
    • G01R33/5615—Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
    • G01R33/5616—Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE] using gradient refocusing, e.g. EPI

Definitions

  • the present invention relates to the diagnostic imaging arts. It finds particular application in conjunction with open MRI systems operating diffusion detection sequences and will be described with particular reference thereto. It will be appreciated, however, that the present invention is useful in conjunction with other systems, such as higher field bore type systems, and is not limited to the aforementioned application.
  • a main magnetic field B 0 is generated through an imaging region wherein is located a subject.
  • Radio frequency (RF) coils transmit RF pulses into the imaging region exciting and manipulating dipoles within the subject.
  • Gradient coils superimpose gradient magnetic fields on the main magnetic field in order to spatially and spectrally encode the excited dipoles .
  • Diffusion weighting sequences detect the movement of water in the subject on the cellular level. These sequences typically detect the movement of water on the order of a few microns, or about the distance it takes to cross a cell membrane. Echo planar imaging (EPI) sequences have been used to detect diffusion in a magnetic resonance scan. Although fast in data acquisition, EPI sequences tend to be very motion sensitive and have relatively low signal to noise ratios (SNR) .
  • SNR signal to noise ratios
  • Rotating k-space diffusion sequences without phase encoding are also used. These sequences are typically more resilient to patient motion, and have higher SNR. However, they take much longer than an EPI sequence, typically on the order of three to four minutes. Another drawback of this type of sequence is that it tends to put heavy loads on the gradient equipment, and is not implementable in all present day MRI scanners. In addition, high, rapidly changing gradient fields can add to patient discomfort.
  • FSE Fast spin echo
  • the present invention provides a new and improved method and apparatus that overcomes the above referenced problems and others .
  • a method of magnetic resonance is provided. Resonance is excited in selected dipoles of a .subject in an imaging region. The resonance is refocused with an inversion pulse, and at least two gradient recalled echos are acquired. Data is collected until enough is present to be reconstructed into an image representation to the subject.
  • a magnetic resonance apparatus In accordance with another aspect of the present invention, a magnetic resonance apparatus is provided.
  • a main magnetic assembly generates a main magnetic field through a subject in the imaging region.
  • An RF coil assembly transmits RF pulses into the imaging region.
  • a gradient coil assembly superimposes gradient fields on the main magnetic field inducing at least two gradient recalled echos .
  • a receiver receives magnetic resonance signals from the imaging region, and a reconstruction processor reconstructs the received magnetic resonance into an image representation.
  • Another advantage resides in higher signal to noise ratios in diffusion weighting imaging.
  • Another advantage resides in more robust data acquisition schemes.
  • Another advantage resides in reduced RF and gradient loads .
  • the invention may take form in various components and arrangements of components, and in various steps and arrangements of steps.
  • the drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention.
  • FIGURE 1 is a diagrammatic illustration of a magnetic resonance imaging apparatus in accordance with the present invention.
  • FIGURE 2 is a pulse sequence diagram illustrating a diffusion weighting pulse sequence in accordance with the present invention
  • FIGURE 3 is a preferred trajectory through k-space, generated by multiple iterations of the pulse sequence of FIGURE 2.
  • a subject is disposed in an imaging region 10 of an magnetic resonance apparatus.
  • an open magnetic resonance apparatus is utilized, however, bore type machines have also been contemplated.
  • the subject is disposed in the apparatus between an upper pole assembly 12 and a lower pole assembly 14.
  • gradient coils 24, 26 transmit gradient pulses into the imaging region.
  • the pulses are controlled by a gradient field controller 28 and amplified by gradient amplifiers 30 then transmitted to the gradient coils 24,26.
  • the gradient field controller 28 includes three specific gradient synthesizers which are utilized in constructing the gradient sequence.
  • a diffusion gradient synthesizer 32 synthesizes gradients that sensitize the magnetic resonance apparatus to the diffusion of water or other molecules in the subject.
  • a frequency encoding synthesizer 34 synthesizes gradient pulses that frequency encode resonance in the subject as well as induce gradient recalled echoes in the subject.
  • the third gradient synthesizer is a slice select gradient synthesizer 36.
  • the slice select synthesizer creates gradient pulses that will limit a region of interest within the subject to a slab or a slice.
  • Upper and lower RF coils 40, 42 transmit RF pulses into the imaging region 10.
  • the pulses are transmitted to the coils 40, 42 by at least one RF transmitter 44, preferably digital.
  • the RF pulses are generated by an RF pulse controller 46.
  • the gradient field controller 28 and the RF pulse controller 46 are both controlled by a sequence controller 48 which retrieves desired sequences from a sequence memory 50.
  • the RF coils 40, 42 or other local receive coils detect the resonance signals.
  • the resonance signals are received by at least one receiver 52 and processed by a reconstruction processor 54 which applies a one dimensional Fourier transform or other appropriate reconstruction algorithm to the detected resonance signals.
  • the processed signals are stored in a magnitude memory 56.
  • a backprojection processor 58 backprojects the image magnitudes producing an image representation that is stored in a volumetric image memory 60.
  • An image processor 62 extracts portions of the image representation from the image memory 60 and formats them for display on a human readable display 62 such as a video monitor, LCD display, active matrix monitor, or the like.
  • the preferred pulse sequence generates multiple gradient recalled echoes. Magnetic resonance data is read from these echoes in the presence of a plurality of different gradients. Slice select gradients are applied to reduce the imaging volume to a selected slice or slab within the subject. Diffusion gradients and frequency encoding gradients are applied preferably such that their sensitivities are orthogonal to one another. In the preferred embodiment , data is read in the absence of phase encoding gradients.
  • a 90° RF excitation pulse 70 is applied in the presence of a slab select gradient 72.
  • the excitation pulse 70 preferably tips magnetic dipoles selected by the slab select gradient 72 into the transverse plane, that is, approximately 90 ° .
  • 90° of tip yields a relatively strong signal, in comparison to lesser degrees of initial tip. It is to be understood that other tip angles are possible, with 90° being preferred as it yields a higher SNR with a possibility for the most gradient recalled echoes .
  • the dephase gradient is composed of a y-component 74a and an x- component 74b.
  • the x and y directions refer to the orthogonal directions in the excited slab, and they also define the directions k x and k y in k-space.
  • the purpose of the dephase gradient is to form an echo in the first read gradient event. Alternatively, it may be applied after the refocusing pulse with opposite sign.
  • the two portions of the dephase gradient 74 combine to define a directional vector of sensitivity in k- space .
  • a first portion of a diffusion sensitivity gradient 76 is applied. Similar to the dephase gradient 74, the first portion of the diffusion gradient is divided into a y-component 76a and an x-component
  • the diffusion sensitivity gradient 76, 82 detects the diffusion of selected molecules, preferably water, during times when it is active.
  • the first part 76 and the second part 82 of the diffusion sensitivity gradient are preferably disposed symmetrically in time about the 180° refocusing RF pulse 78.
  • the gradient lobes 76 and 82 should have the same area.
  • a first frequency encode gradient 84 commonly known as a read gradient
  • the first read gradient 84 is composed of a y-component 84a and an x-component 84b.
  • the two components define a directional vector that is approximately perpendicular to the directional sensitivity of the diffusion gradient 76, 82 and has the same direction as the dephasing gradient 74.
  • the area underneath lobes of the first read gradient 84 is approximately twice the size of the area underneath the dephase gradient 74.
  • a reversal gradient 86 is applied to the imaging region.
  • the reversal gradient similar to the other gradients has a y- component 86a and an x-component 86b.
  • the reversal gradient effectively resets the data readout in k-space, and defines where one data line stops and the next one begins.
  • another read gradient 88 is applied to form a second data line in k-space.
  • the second read gradient comprises a y-component 88a and an x-component 88b.
  • the second read gradient 88 is slightly different than the first read gradient 86.
  • the read direction of the second read gradient 88 is shifted less than one degree from the read direction of the first read gradient 84.
  • data lines are stepped in a rotational fashion about a center of k-space 100.
  • the first read gradient 84 generates a data line 102 in k-space.
  • the second read gradient 88 generates a second data line 103 with a slightly different read direction than the first data line 102.
  • the preferred sequence makes 256 steps around 180° making the angle 106 between each data line approximately 0.70°. Of course, more or fewer steps can be taken, it is preferred, however, that the angle between data lines be no greater than 10° as the sequence will become sensitive to motion of the subject, as discussed in the background. Additional data lines are generated with additional cycles of the described two echo embodiment.
  • additional data lines can be read by utilizing additional reversal gradients.
  • the second reversal gradient is approximately the same amplitude of the reversal gradient 86, with a small change in the direction of the third read gradient, producing data line 104.
  • about four gradient recalled echoes may be induced from one RF excitation pulse. After four echoes, the phase errors accumulated in the gradient recalled echoes may become too large.
  • RF echoes 90 and 94 occur in time windows 92, and 96 respectively and are disposed symmetrically about a time TE.
  • the group of echoes is centered on the time TE, for example, in a three echo embodiment, the second echo is centered on the time TE.
  • the 180° refocusing pulse 78 occurs at a time TE/2, as implied, the time TE/2 occurs at half the value of time TE.
  • the RF echoes are received in the absence of phase encoding.
  • Projection reconstruction methods are used to form the image .
  • the receiver 52 receives a real part and an imaginary part of the magnetic resonance signals.
  • the reconstruction processor 54 adds the squares of the real and imaginary parts and takes the square root. Simplified, if the real part is x and the imaginary part is y the reconstruction processor performs the operation X ⁇ l— 2 to obtain the magnitude data of the received
  • no reversal gradients are used. Instead, subsequent gradients are substantially opposite each other. That is, if the first gradient lobe is positive, the second is negative, and so forth.
  • the frequency encoding gradients run subsequently with no interruption, or possibly with a small gradient pulse in- between to adjust the starting point of the data line.
  • the data lines are read in opposite directions, and the arrowheads in FIGURE 3 would likewise alternate.
  • the diffusion gradient pulses 76, 82 are both applied before the refocusing pulse 80.
  • the pulses have opposite signs.
  • the diffusion gradient pulses 76, 82 contain a component in the direction of the slice select gradient . Despite this modification, the requirement that the diffusion gradient be orthogonal to the read gradient can still be fulfilled.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Vascular Medicine (AREA)
  • General Health & Medical Sciences (AREA)
  • Radiology & Medical Imaging (AREA)
  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Magnetic Resonance Imaging Apparatus (AREA)

Abstract

Dans un appareil d'imagerie par résonance magnétique, un sujet est placé dans une zone d'imagerie (10). Un équipage magnétique (16, 18) crée un champ magnétique principal (Bo) à travers la zone d'imagerie (10). Une séquence d'impulsion de fréquence radio et de manipulations de champ de gradient excite et manipule la résonance magnétique entre lesdits pôles du sujet. Cette séquence comprend une impulsion d'excitation RF de 90° et une impulsion de recentrage de 180° comme dans l'art d'imagerie d'écho spin standard. La séquence comprend des impulsions de gradient qui induisent au moins deux échos RF rappelés par gradient (98, 100) tout en supprimant les signaux d'écho spin. Elle comprend également des gradients sensibles à la diffusion (76, 82) qui captent le mouvement de l'eau ou d'autres molécules durant la séquence d'imagerie. Les échos induits par gradient (98, 100) sont symétriquement disposés sur une certaine durée (TE). L'appareil comprend également un processeur de reconstruction (54) qui prend des parties réelles et imaginaires de signaux de résonance magnétique reçus et les convertit en données quantitatives de signaux. Ces données quantitatives sont utilisées à la place du codage de phase dans la reconstruction.
EP02782317A 2001-11-20 2002-11-19 Sequence de reconstruction de projection de type a echo de gradient multiple destinee a une irm et notamment a une irm a diffusion ponderee Expired - Lifetime EP1449004B1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US988465 1997-12-10
US09/988,465 US6445184B1 (en) 2001-11-20 2001-11-20 Multiple gradient echo type projection reconstruction sequence for MRI especially for diffusion weighted MRI
PCT/US2002/037000 WO2003044555A1 (fr) 2001-11-20 2002-11-19 Sequence de reconstruction de projection de type a echo de gradient multiple destinee a une irm et notamment a une irm a diffusion ponderee

Publications (2)

Publication Number Publication Date
EP1449004A1 true EP1449004A1 (fr) 2004-08-25
EP1449004B1 EP1449004B1 (fr) 2008-12-31

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EP02782317A Expired - Lifetime EP1449004B1 (fr) 2001-11-20 2002-11-19 Sequence de reconstruction de projection de type a echo de gradient multiple destinee a une irm et notamment a une irm a diffusion ponderee

Country Status (5)

Country Link
US (1) US6445184B1 (fr)
EP (1) EP1449004B1 (fr)
JP (1) JP2005509509A (fr)
DE (1) DE60230662D1 (fr)
WO (1) WO2003044555A1 (fr)

Families Citing this family (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6751495B2 (en) * 2000-03-31 2004-06-15 Brigham & Womens' Hospital Method of fast and reliable tissue differentiation using diffusion-weighted magnetic resonance imaging
US7193416B2 (en) * 2001-12-10 2007-03-20 Koninklijke Philips Electronics N.V. Open magnetic resonance imaging (MRI) magnet system
DE10219528A1 (de) * 2002-05-02 2003-11-13 Philips Intellectual Property Schnelles Kernresonanz-Bildgebungsverfahren mit Gradienten-Echos
WO2007038206A1 (fr) * 2005-09-22 2007-04-05 Wisconsin Alumni Research Foundation Reconstruction par retroprojection a forte contrainte en rmi ponderee par diffusion
US8406849B2 (en) * 2006-03-31 2013-03-26 University Of Utah Research Foundation Systems and methods for magnetic resonance imaging
EP1959397B1 (fr) * 2007-02-19 2019-08-07 Wisconsin Alumni Research Foundation Reconstruction HYPR itérative d'images médicales
US8320647B2 (en) 2007-11-20 2012-11-27 Olea Medical Method and system for processing multiple series of biological images obtained from a patient
US8339138B2 (en) * 2008-10-15 2012-12-25 University Of Utah Research Foundation Dynamic composite gradient systems for MRI
US8274283B2 (en) * 2009-04-27 2012-09-25 Siemens Aktiengesellschaft Method and apparatus for diffusion tensor magnetic resonance imaging
WO2013001415A1 (fr) * 2011-06-28 2013-01-03 Koninklijke Philips Electronics N.V. Irm présentant une séparation de différentes espèces chimiques à l'aide d'un modèle spectral
EP2610632A1 (fr) 2011-12-29 2013-07-03 Koninklijke Philips Electronics N.V. Imagerie par RM avec séparation eau/graisse de type Dixon et connaissance préalable de l'inhomogénéité du champ magnétique principal
EP2626718A1 (fr) * 2012-02-09 2013-08-14 Koninklijke Philips Electronics N.V. IRM avec correction de mouvement utilisant des navigateurs acquis avec une technique de Dixon
CN103513202B (zh) * 2012-06-16 2016-04-27 上海联影医疗科技有限公司 一种磁共振成像中的dixon水脂分离方法
KR101301490B1 (ko) 2012-06-19 2013-08-29 한국과학기술원 자기공명영상장치 및 확산강조영상획득방법
CN102928796B (zh) * 2012-09-28 2014-12-24 清华大学 快速扩散磁共振成像和重建方法
DE102012217992A1 (de) 2012-10-02 2014-04-03 Siemens Aktiengesellschaft Verfahren und Magnetresonanzanlage zur Erfassung von MR-Daten mit Diffusionsinformation
DE102012217997A1 (de) 2012-10-02 2014-04-03 Siemens Aktiengesellschaft Verfahren zur zeitabhängigen Intensitätskorrektur von diffusionsgewichteten MR-Bildern und Magnetresonanz-Anlage
US9897677B2 (en) * 2013-09-04 2018-02-20 Samsung Electronics Co., Ltd. Method for correcting errors associated with asynchronous timing offsets between transmit and receive clocks in MRI wireless radiofrequency coils
KR101560463B1 (ko) * 2013-12-30 2015-10-16 가천대학교 산학협력단 오프 공명 라디오주파수 펄스를 사용하는 자기 공명 영상 시스템에서 인공물 및 원하지 않는 신호를 제거하는 자기 공명 영상 획득 방법
WO2016077438A2 (fr) 2014-11-11 2016-05-19 Hyperfine Research, Inc. Séquences d'impulsions pour résonance magnétique à faible champ
US10088539B2 (en) 2016-04-22 2018-10-02 General Electric Company Silent multi-gradient echo magnetic resonance imaging
TW202012951A (zh) 2018-07-31 2020-04-01 美商超精細研究股份有限公司 低場漫射加權成像
US11202583B2 (en) * 2019-02-07 2021-12-21 Yale University Magnetic resonance gradient accessory providing tailored gradients for diffusion encoding
CN111839515B (zh) * 2019-04-26 2024-03-08 西门子医疗系统有限公司 利用磁共振成像的胎儿胼胝体体积的测量方法及磁共振成像装置
WO2021108216A1 (fr) 2019-11-27 2021-06-03 Hyperfine Research, Inc. Techniques de suppression de bruit dans un environnement d'un système d'imagerie par résonance magnétique

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4833407A (en) 1987-06-24 1989-05-23 Picker International, Inc. Scan time reduction using conjugate symmetry and recalled echo
US5270654A (en) * 1991-07-05 1993-12-14 Feinberg David A Ultra-fast multi-section MRI using gradient and spin echo (grase) imaging
US5300886A (en) * 1992-02-28 1994-04-05 The United States Of America As Represented By The Department Of Health & Human Services Method to enhance the sensitivity of MRI for magnetic susceptibility effects
US5833609A (en) 1996-11-26 1998-11-10 Picker International, Inc. Rotating diffusion MR imaging reduced motion artifacts

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO03044555A1 *

Also Published As

Publication number Publication date
JP2005509509A (ja) 2005-04-14
EP1449004B1 (fr) 2008-12-31
US6445184B1 (en) 2002-09-03
DE60230662D1 (de) 2009-02-12
WO2003044555A1 (fr) 2003-05-30

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